The present invention relates to a mobile station for a mobile telecommunications system, in particular a mobile handset with an associated headset.
Mobile handsets with associated headsets are in common use. The headset is to enable handsfree operation and may be corded or cordless. The cord of a corded headset has a terminating plug which is inserted into a terminal in the handset to provide an audio path to the headset. A cordless headset is coupled with the handset by a subsidiary wireless link. The arrangement is shown schematically in FIG. 1. A handset 2 has an antenna 4 coupled to a RF front end, or transceiver section, 6. A digital processing section 8 processes incoming and outgoing calls, and provides control functions. Section 8 is connected to a key pad 10, a display 12, a loudspeaker 14 and microphone 16. Loudspeaker 14 and microphone 16 are coupled to section 8 by lines which provide a first audio path indicated as at 18. A second audio path 20 from section 8 is connected to a socket 22 in the handset for connection with a plug 24 attached to one end of a lead or cord 26, the other end of which is connected to a headset 28 comprising headphones 30 and a microphone 32. When the plug 24 is plugged into the socket, audio is automatically routed to the headset. Key pad 10 includes a switch 36 for accepting an incoming call or initiating an outgoing call, and a switch 38 for terminating a call. Switches 36 and 38 are implemented as finger operable button switches.
The mobile station may, throughout the day, be used in a variety of situations. For example, a user may ‘wear’ the headset during use in a motorcar, and then may wind the cord of the headset around the handset and put the handset in his pocket. In this situation, with the corded headset connected to the handset, but not worn on the user's head, it is difficult to answer an incoming call quickly. The user either has to unplug the headset or has to quickly ‘wear’ the headset. With a cordless headset, the difficulty for the user of knowing where the audio is routed, to the handset or headset, is increased.
Thus, there is a problem that may arise in a variety of situations for the user to ascertain where the audio path is routed and what is the most effective way of answering an incoming call. In an extreme situation, an incoming call may be lost.
One possible solution of routing the audio simultaneously both to the handset and to the headset would not be practical, since there would be a great amount of audio feedback resulting in acoustic echo, wherein the handset microphone picks up the generated audio. In addition there would be much degraded ambient noise pick up, adversely affecting listener side tone and send audio noise performance.